V6 1997, Cutting Out/Hunting When Hot

[windywatson]

Well they say it happens in threes,

What with wipers on blink, noisey tappets & now this my third post.

When the van is up to temp and has had a fairly long run, if restarted soon after switching off the engine will fire up ok but will hunt with the revs dropping enough for it to almost stall & then pick up again. If I atempt to pull away with out picking the rev's to much higher that would normally be needed the engine will stall.
I recall reading about similar problem that was to do with air intake pressure/flow or somthing like that, but can't find the item. So where & what do I start to look for to solve this if I can? Or as a DIY mechanic Is there anything that I can actually do, or do I have to entrust this sort of thing to the garage?

Any suggestions?

Cheers

[mikeWalsall]

Maybe a new / clean air filter .. plugs / leads OK .. leads all a tight fit ..??

As a fuel injection system does not have a choke, until the engine is up to temperature, sensors tell the ECU to inject fuel faster ... as a wire come lose from a sensor .. or a dodgy sensor causing to rich a mixture when the engine is up to normal running temperature .. ??

Are all the rubber vacuum pipes 'plugged' in tight with none perished or split as that would affect the engines running, even the gear changes could suffer......

[windywatson]

Thanks for the feedback, I will have to do some basic inspection of the vacum pipe work and wiring around sensors. Any Idea where I need to be looking for the sensors you mention?
The van has had a complete new set of HT equipment (genuine mazda) disy cap, rotor, leads etc so can rule that out.
Expect it may be something simple as a perished pipe some where, just have to start looking.

cheers

[amauvis]

Can't help with Bongo specifically, but with the BMW's I have had, the sensors mentioned above would be the crank or cam position sensors, and the symptoms would be as you described.

[Simon Jones]

You mention on the other thread that you've got LPG. Does it cut out on petrol & LPG?

[mikeWalsall]

Good thinking .... my tick over is OK on petrol ... but not always 100% right on LPG..!!

[windywatson]

Not sure if the LPG convertion will be effecting the starting as at start it's on petrol any way. And I'm not a 100% sure, but thought that LPG would then only cut in at a certain RPM once moving off. However this is a good point. Any LPG experts out there that could throw any light on this?

Cheers

[Simon Jones]

I believe it is based on engine temperature, in which case I would expect it use LPG as soon as restarted when hot. Not had mine converted yet, so can't say for sure.

[mikeWalsall]

The engine always starts on petrol .. even if the engine stops when hot it will start back up on petrol then switch over quickly to LPG...

In an emergency it is also possible to manually hold in the change over button and start on LPG ... but when cold I have found it is impossible to drive away until the engine as warmed up ..

My Toyota switches over from petrol to gas very quickly ... the Bongo is set to switch from petrol when the temperature gauge is up to normal, which in my opinion is to far long using petrol ..

When the engine is hot and the engine running, it is easy to instantly switch from LPG to petrol and vise versa to check if a problem is a associated with gas or petrol..